That's really going to depend on the thickness of the surface that you're attaching the fender to. You'll want the screw length to be longer than the thickness of the fender and the surface you're connecting it to. If you can't use the existing holes, epoxy putty would be a good product to fill them. www.etrailer.com/Trailer-Fenders/etrailer/HP24VR.html
how long should your self tapping screws be? what do you do to the old holes that your aren't using any more?
That's really going to depend on the thickness of the surface that you're attaching the fender to. You'll want the screw length to be longer than the thickness of the fender and the surface you're connecting it to. If you can't use the existing holes, epoxy putty would be a good product to fill them.
www.etrailer.com/Trailer-Fenders/etrailer/HP24VR.html
Should these be sealed against the trailer body with a sealant caulk?
That would be an excellent idea!
www.etrailer.com/Trailer-Fenders/etrailer/HP24VR.html
What would you use?
@@snowfreak207
Some sort of high quality siliconized sealant designed for high flexibility and fluctuating weather conditions